It has been required that the image display surface of an image display device such as a liquid crystal display (LCD) and a cathode ray tube (CRT) display be imparted with abrasion resistance to avoid being scratched upon handling. To meet the request, in general, an optical laminate (hereinafter, it may be referred to as a hard coat film), which comprises a hard coat (HC) layer provided on a substrate film, is used to increase the abrasion resistance of the image display surface of an image display device.
Examples of techniques of hardening a plastic surface generally include methods of forming a metallic thin film by coating an organosiloxane-based or melamine-based heat-curable resin, by the vacuum deposition method or sputtering method using such a resin, and by coating a polyfunctional acrylate-based active energy ray-curable resin.
As another method of improving the hardness of a hard coat layer, there may be a method of adding inorganic fine particles, generally in which a hard coat film provided with a hard coat layer having inorganic fine particles added on a substrate film is produced.
Meanwhile, an optical film used as an antireflection film attached or disposed on the surface of a display for the purpose of antireflection of outside light to improve images is known (for example, see Patent Literature 1).
The optical film comprises a cured layer formed on a transparent plastic substrate film. Patent Literature 1 discloses that an apparently low refractive index layer can be formed, and excellent antireflective properties can be obtained by unevenly distributing hollow silica being low-refractive-index fine particles on the surface side of the cured layer (the side opposite to the substrate film side). Patent Literature 1 discloses that hollow silica having an average particle diameter of 30 nm or more to further decrease refractive index by increasing the ratio of voids, and hollow silica having an average particle diameter of 40 nm is used in Examples. In order to unevenly distribute hollow silica on the surface side of the cured layer, hollow silica is subjected to surface treatment with a fluorine-containing compound to decrease surface free energy.